// 这个接口属性接口，专门用来约束属性
interface IUser {
    id:number,
    name:string,
    address?:string
}

interface IStu {
    id:number,
    name:string,
    age:number
}

// 类型声明
type tea = IUser | IStu | null

let user:IUser = {id:1,name:"xiaowang",address:"武侯区"}

let student:IStu = {id:100,name:"小飞",age:10}

let teacher:tea = null

export {}